Extremum Seeking-Based Braking Friction Force Maximization Algorithm Using Fuzzy Logic Without Slip Ratio for ABSs

In this paper, we propose an extremum seeking-based algorithm using fuzzy logic for maximizing the braking friction force in anti-lock brake systems (ABSs) without relying on vehicle speed information and slip ratio dynamics. Many current ABSs algorithms utilize slip ratio as a control parameter. If the slip ratio is inaccurately measured, the braking performance of the ABSs may not be optimal. To address this, we propose a method to achieve maximum friction force by designing a reference generator that generates the control inputs for the ABSs without requiring slip ratio information. We design an extended state observer that can estimate the braking friction force and braking friction coefficient. Based on the estimated friction force, the desired wheel cylinder pressure (WCP), which is the control input of the hydraulic brake system, is generated to converge to the maximum friction force using the extremum seeking control algorithm. To achieve improved braking performance, the initial desired WCP is calculated using fuzzy logic for quick convergence to the optimal region. The proposed method is experimentally validated using a hardware-in-the-loop simulation, which includes components such as MATLAB/Simulink, CarSim, SCALEXIO real-time system, and a hydraulic brake system.